In a marine vessel operated by using liquefied gas such as LNG (=Liquefied Natural Gas) the fuel is normally stored in tank approximately at a temperature of minus 162° C. in liquid form. Before feeding to an engine the liquid fuel must be evaporated into gaseous form and also heated to suitable level, which requires heat energy.
Particularly in passenger cruisers there are several entities in which a process medium must be cooled or in connection with which heat should be extracted, like cold storage rooms etc. These both actions require work to be done which consumes energy. Additionally the targets in which the cool is needed are usually widely distributed in the vessel.
An object of the invention is to provide an arrangement and a method, which simultaneously provides a solution to both of the problems with minimized energy consumption.